Not only did tissue from the afternoon group show less damage, it also regained the ability to contract more quickly in lab tests that mimicked the heart refilling with blood.

High-risk patients

A genetic analysis of the same tissues showed hundreds of genes linked to circadian rhythms were more active in the afternoon group, suggesting that the heart, too, is influenced by our biological clock.

Montaigne and his team deleted and replaced the corresponding genes in mice to study the impact on the transition between sleep to wakefulness, and vice versa.

Finally, they identified candidate drugs that might modulate these genes in such a way as to protect the heart during surgery.